We propose to investigate further: (1) The relation of cyclic starvation to pathological iron storage in rats. (2) The biological control (biochemical and genetic) of isoferritin production by normal and cancer cells. (3) Intracellular sites at which molecules of ferritin are assembled from protein subunits and iron. (4) Abnormalities of bile secretion in rat livers that are overloaded with iron.